Process for cracking or steam reforming hydrocarbons using an alkali polyaluminate catalyst

ABSTRACT

A CATALYST FOR CATALYTIC CRACKING OR STEAM REFORMING OF HYDROCARBONS AND THE PROCESS FOR PRODUCING THE SAME, IN WHICH SAID CATALYST BEING OF ALKALI POLYALUMINATES, OR 2% OR MORE OF ALKALI POLYALUMINATES SUPPORTED ON REFRACTORY CARRIER, OR THE ABOVE-MENTIONED CATALYSTS WHICH ARE ADDED WITH 0.5% OR MORE OF CHROME OR A METAL SELECTED FROM GROUP VIII OF THE PERIODIC TABLE, OR A MIXTURE THEREOF.

June 18, 1974 GQRQ YAMAGUCH] ETAL 3,817,726 PROCESS FOR CRACKING ORSTAEM REFORMING HYDBOCARBONS USING AN ALKALI POLYALUMINATE CATALYSTOriginal Filed April 1, 1970 2 3" Al 0 w H Bl E o COMMERCIALLY AVAILABLE'5 CATALYST DURATION OF REDUCTION (hours) United States Patent 63,817,726 PROCESS FOR CRACKING R STEAM REFORM- ING HYDROCARBONS USING ANALKALI POLYALUMINATE CATALYST Goro Yamaguchi, 1554 Tsuda-machi,Kodaira-shi, Tokyo, Japan; and Susumu Komatsu, 1099 Uraimbe, Bizen-cho,Wake-gun; Kazuhiro Yoshizaki, 98 Uraimbe, Bizen-cho, Wakeand TetsuoFukumoto, 783 Uraimbe, Bizencho, Wake-gun, all of Okayama, JapanOriginal application Apr. 1, 1970, Ser. No. 24,543, now Patent No.3,694,379, dated Sept. 26, 1972. Divided and this application June 29,1972, Ser. No. 267,614 Claims priority, application Japan, Aug. 28,1969, 44/ 67,562 Int. Cl. C01b 2/14 U.S. Cl. 48-214 12 Claims ABSTRACTOF THE DISCLOSURE A catalyst for catalytic cracking or steam reformingof hydrocarbons and the process for producing the same, in which saidcatalyst being of alkali polyaluminates, or 2% or more of alkalipolyaluminates supported on refractory carrier, or the above-mentionedcatalysts which are added with 0.5% or more of chrome or a metalselected from Group VIH of the Periodic Table, or a mixture thereof.

This is a division of application Ser. No. 24,543, filed Apr. 1, 1970now Pat. No. 3,694,379.

This invention relates to a catalyst composition for catalytic crackingor steam reforming of hydrocarbons, consisting of one member selectedfrom the group of alkali polyaluminates (Ii-alumina; or R 0-11Al O13'-alumina; or R O-7-8Al O fi"-alumina; or R O--6Al 0 (wherein R is Naor K)), or a catalyst being supported on refractory carrier containingat least 2% by weight of an alkali polyaluminate, calculated as analkali metallic oxide, and it also relates to a process for producingthe same. Further, it relates to a catalyst composition for catalyticcracking and steam reforming of hydrocarbons, the catalyst beingsupported on refractory carrier, characterized in that it is prepared byadding at least 0.5% of chrome or a metal selected from Group VIII ofthe Periodic Table or a mixture thereof, calculated as an oxide, to onemember selected from the group of alkali polyaluminates or otherrefractory carrier material incorporated with at least 1.0% of an alkalipolyaluminate, calculated as an alkali metallic oxide, and it alsorelates to a process for producing the same.

Generally, when hydrocarbons are subjected to catalytic cracking orsteam reforming over catalysts, catalysts will maintain their activityfor a short time and allow carbon to deposit easily thereon therebynecessitating repeated regeneration of catalysts by burning out thecarbon deposited on the deactivated catalyst. This regeneration processof catalysts not only makes the operation of a reaction furnacecomplicated but also is time-consuming and inefl'icient. If thisregeneration is neglected or the operation of the furnace is continuedby using insufiiciently regenerated catalysts, carbon will be depositedin ice pores of catalysts, thereby destroying the structure thereof insuch a way as to weaken the bond among the constituents thereof,possibly resulting in the collapse of a part or all of constituents.

This is reported to be due to the reaction of aromatic substances, whichare intermediate products obtained by the decomposition of hydrocarbons,at the acidic point of the catalysts. In particular, even catalysts,which consists only of nickel and alumina and are free of acidic substances such as Si0 and the like, will be unable to prevent thedeposition of carbon thereon if used for a long time, because of thepresence of acidic point of Lewis acid, a non proton acid, in thealumina (A1 0 In an attempt to overcome such disadvantages, improvementsin catalysts composition have been proposed and practically made, one ofthe improvements being such as the addition of the chromate ordichromate of an alkali metal or alkali metallic salt such as carbonateto the catalysts to neutralize the acidic point thereof (Japanese PatentGazette of Publication No. Sho 40 26,413). However, the catalystsincorporated with said additive have been proved to have a shortercatalytic life because, when used, they are exposed to high temperaturesunder a reducing atmosphere whereby the alkali metal present in theadditive is gradually volatilized in such a manner that an approximatehalf of the amount of the alkali metal is lost by volatilization afterone-year use of the catalysts.

Various studies were made by the inventors, with the object of allowingthe catalysts to contain an alkali metal in an amount enough to keepthem neutral and in the nonvolatile form during their use. As a resultof the studies, it has been found that the object is satisfactorilyachieved by the addition of the polyaluminate of an alkali to thecatalysts.

s-A1 o,, which is a mineral having the composition of R 0-11Al O(wherein R is Na or K), has been known as one of the conventional alkalipolyaluminates; and the existence of two new alkali polyaluminates,these being B'-alumina and fi"-alumina respectively having thecomposition of R O-7-8Al O and R O-5-6Al O (wherein R is K or Na), whichhave a higher content of an alkali metal, has been found by Yamaguchiand others who are among the inventors (refer to Bulletin of theChemical Society of Japan, vol. 41, No. 1, pp. 93-99 (1968)). The termalkali polyaluminates used herein designates sodium and potassiumpolyaluminates in which both said conventional and new polyaluminatesare included. These minerals will decompose at a low rate even whenexposed to a high-temperature reducing atmosphere for a long time,whereby the alkali metal presentv in the minerals is diflicult tovolatilize and consequently hardly decreases in amount.

The accompanying drawing shows the results of a test in which apotassium polyaluminate (ff-A1 0 containing 12.01% of K 0) andcommercially available nickel catalyst incorporated with potassium salt(containing 8.12% of K 0) were heated in the hydrogen flow at atemperature of 1000 C. for 1500 hours in order to study how thepotassiums present therein volatilize during heatmg.

It has been found that the alkali present in said alkali polyaluminateis volitalized at a considerably lower rate than the one present incommercially available catalysts. Therefore, such an alkalipolyaluminate, when used as a catalyst, will serve to keep the catalystneutral for a longer time and will be remarkably effective in inhibitingthe deposition of carbonaceous substances on the catalyst due to thefact that a portion of the alkali metal moves within the catalystthereby combining principally with the acidic point of the catalyst.

When hydrocarbons are subjected to catalytic cracking in the presence ofsteam by using a catalyst containing said alkali polyaluminate or acatalyst prepared by adding at least 2% of an alkali polyaluminate,calculated as an alkali metallic oxide (Na o or K to other refractorycarrier, oxidation reaction, i.e., water gas reaction is especiallypromoted. Therefore, the amount of carbon to be deposited on thecatalyst is very small. Formation of tar is also negligible. Thus, a gashaving a high content of hydrogen (H and consisting of methane (CHethylene (C H carbon dioxide (CO and a small amount of carbon monoxide(CO) is obtained. This gas decomposes to such an extent where otherheavy hydrocarbons are hardly noticed. It has been found that town gashaving an ideally high calorific value can be produced in this way at anextremely low cost.

In catalytic cracking of hydrocarbons having 5 to 6 carbon, such asnaphtha or the like, the space velocity of liquid should be preferablylow, that is, approximately 1, if it is desired to produce town gas. Ahighly combustible and safe gas having a calorific value of as high as6000 kcal./Nm. and containing hydrogen (H methane (CH etc. in a greatquantity and being free from carbon monoxide (CO) can be produced at areaction temperature of 800 C. 0n the other hand, in producing ethylene(C H the space velocity of liquid should be preferably higher, that is,about 5-10, whereby a gas having a good yield of ethylene can beproduced.

Another important characteristic of this catalyst is that it has thequite same effect as stated above in catalytically cracking heavyhydrocarbons of crude oil and the like thereby producing a gas having acalorific value of as high as 6000-7000 kcaL/Nm. and being free ofhydrocarbons above propylene.

Steam reforming reaction of hydrocarbons is remarkably promoted byadding at least 0.5% of chrome oxide and a metallic oxide of Group VIIIof the Periodic Table to a catalyst containing an alkali polyaluminateor a catalyst prepared by incorporating at least 1.0% of alkalipolyaluminate, calculated as an alkali metallic oxide (Na O or K 0), toother refractory carrier material. A gas that has reached equilibriumisproduced at a temperature of about 400 C. and above, whereby a quiteactive catalyst can be obtained. When it is desired to produce methane(CH in a great quantity at a high pressure and low temperature or whenit is desired to produce hydrogen (H continuously in a great quantity ata high pressure and high temperature, the catalytic metal oxide shouldbe added in a comparatively great quantity, that is, for more than 10%.Since such a catalyst can produce a gas composition that has reachedequilibrium in accordance with the reaction pressure, reactiontemperature, steam-to-carbon ratio, amount of carbon and hydrogenpresent in the material hydrocarbon and etc., it is possible to changethe composition of a gas freely and easily in a wide range in accordancewith the requirements.

In case when sulfur compounds are present in a material hydrocarbon, acatalyst may be preferably used at a reaction temperature of 750-800 C.which contains an alkali polyaluminate or is prepared by adding at least1% of alkali polyaluminate, calculated as an alkali metallic oxide, to arefractory carrier, or which is prepared by adding a comparatively smallamount, that is, 05-20%, of chrome oxide or a metallic oxide of GroupVIH of the Periodic Table or a mixture thereof to said catalyst. If sucha catalyst is used, catalytic cracking and steam reforming reaction canhe proceeded without being poisoned by sulfur. In this case, catalyticcracking may be performed over the former alkali polyaluminate whichdoes not contain any metal in order to produce a gas having'a calorificvalue of more than 6000 kcal./Nm. For production of a gas having acalorific value of about 4000 kcal./Nm. the latter catalyst containingabout 0.5-2.0% of metals is more suitable.

Catalysts can be prepared by any one of the following processescomprising;

( 1) adding a suitable bonding agent to an alkali polyaluminate inpowder form and then molding the resulting mixture into tablets, pieceshaving Raschig ring-like shape or other suitable shapes, or sinteringsaid mixture by firing;

(2) mixing a refractory carrier material with a finely powdered alkalipolyaluminate so as to contain alkali metal in an appropriate quantityand then molding the resulting mixture into a suitable shape by use of asuitable bonding agent, or sintering said mixture by firing;

(3) adding one member selected from the group of alkali polyaluminatesin powdered form to a solution of chrome or a metallic salt of Group VIHof the Periodic Table to precipitate metals, filtering the resultingslurried mixture, after agitation, with subsequent washing and thenmolding said mixture into a suitable shape by use of a bonding agent;

(4) impregnating a sintered alkali polyaluminate or a sintered mixtureof an alkali polyaluminate and a refractory carrier material of anappropriate shape into a solution of chrome or a metallic salt of GroupVIII of the Periodic Table and then heating the resulting mixture at atemperature of about 600 C.;

(5) mixing chrome or a metallic salt of Group VIII of the Periodic Tablewith a finely powdered member of the group of alkali polyaluminates or arefractory carrier material containing an appropriate amount of any oneof alkali polyaluminates, and then molding the resulting mixture by useof a suitable bonding agent, or sintering said mixture by firing.

Refractory materials which may preferably be used as carriers for thecatalyst include, neutral or basic oxides (such as A1 0 Cr O CaO, MgOand the like), or a mixture thereof. As such carriers, there may also beused acidic oxides (such as SiO TiO Zr0 and the like) or a mixturethereof, as well as other refractory oxide materials including a mixtureof neutral, basic and acidic oxides or a sintered mixture thereof (suchas and the like). The alkali polyaluminate, if added in an amount of1.0% and more, calculated as alkali metal oxide, will be satisfactorilyeffective in inhibiting the deposition of carbon when a neutral or basicoxide material is used as a carrier, while the alkali polyaluminate willhave to be increased in amount in proportion to the amount of acidicoxide when acidic oxide (SiO such as aluminasilicates and the like areincluded in the carrier. In this connection, the B- or fi'-alkalipolyaluminate should preferably be added in an amount at least 2.5 timesthat of the acidic oxides contained in the catalyst composition in orderto obtain the maximum inhibiting effect on the deposition of carbon onthe catalyst composition. It is thus advisable that the catalystcomposition should contain alkali-richer fi"-alkali polyaluminate if italso contains acidic oxides in an amount of 20% or more (in this case,the amount of the alkali polyaluminate added being at least twice aslarge as the acidic oxides contained).

This invention will be better understood by the following examples.

EXAMPLE 1 A potassium polyaluminate (ff-A1 0 prepared by mixing 6molecular weight aluminum hydroxide and 1 molecular weight potassiumcarbonate and then firing the resulting mixture at a temperature of 1400C., is pulverized, to which CMC solution of 1.8% in concentration isadded in the amount of 13%. The mixture thus obtained, after beingkneaded, is molded into tablets of mm. in diameter and 7 mm. in height,which is then fired at a temperature of 1500 C. The catalyst thusobtained has the following chemical composition and physical properties.

Shown in the following table are the results of a test in which saidcatalyst composition was used in 24-hour continuous catalytic crackingof naphtha, whose boiling point range is from 30 C. to 88 C., specificgravity is 0.6455 (71 and sulfur content is 130 p.p.m.

For the purpose of comparison, the results of a test in which A1 0 wasused as a heat medium under the same condition are shown below.

Chemical composition of catalyst (percent):

Chemical composition of catalyst (percent) SiO 1.1

CaO 0.5

MgO 48.1

RULES OF CATALYTIC CRACKING Operation hour hours hours hours hours hoursReaction temp., C 800 796 810 800 793 Steam-to-carbon ratio, kg./l 1.201796 810 800 793 Space velocity 1. 0 796 810 800 793 Composition ofgaseous mixture produced, percent Amount of gas produced, rnfi/kl 1, 2051, 53 l, 242 1, 268 1:260

Calorifie value, kcalJrn. 6, 230 6, 725 6, 855 7, 092 7, 315

Etficiency oi gasification, 101. 0 112. 5 114. 6 120. 1 124. 9

percent.

EXAMPLE 3 B-Al O (Na O'11A1 3), fused alumina abrasive, in fine powdersis mixed with alumina cement at the ratio of 70 to 30 by part which arethen formed into pellets RESULTS OF CATALYTIC CRACKING Operation hour 1hour 20 hours Catalyst of Heat medium Catalyst of Heat medium thisinvention A1203 this invention A1203 Reaction temp., C 750 800 750 800750 800 750 800 Steam-to-carbon ratio, kg. [1 1. 516 800 750 800 750 800750 800 Space velocity 1. 0 800 750 800 750 800 750 800 Composition ofgaseous mixture produced, percent:

000 9. 93 12. 12 2. 13 3. 78 7. 10. 68 1. 07 2. 68 CO- 1. 10 4. 70 1.41 1. 21 1. 05 2. 99 0. 72 1. 48 CH4- 19. 69 18. 01 31. 53 31. 92 23. 9320. 39 33. 04 33. 66 C-fFh 1. 35 1. 10 2. 68 1. 17 1. 46 0. 98 3. 38 1.31 (3,111 17. 82 12. 71 27. 10 20. 35 20. 99 15. 78 27. 85 22. 15C-iT-TA 2. 77 0. 48 6. 73 0. 80 4. 09 0. 83 7. 37 1. 12 n-C4Hm 0. O8 0.23 1-C4Hs 0. 26 0. 19 ISO-C4Ha-- 0. 24 0. 77 0. 41 TI-Z-Cafi 0. 11 0. 16l-B-CA K 0. 39 1. 18 1. 38 Iso-CaHrz- 0. 19 0. 38 0. 40 .03,, 0. 32 0.46 0. 32 L 40. 32 49. 11 23. 58 20. 22 34. 61 N 1. 25 0. 20 0. 47 0. 160 0. 12 Amount of gas produced, mfi/kl l, 050 1, 375 618 698 992 1, 335536 607 Calorific value, kcaL/mfi' 6, 916 5, 574 10, 722 8, 701 8, 1866, 173 11, 258 8, 366 Eflieiency of gasifieation, percent 98. 3 103. 289. 5 82. 4 109. 8 111. 5 81. 2 68. 5 0. 75 0. 84 2. 37 4. 99

Carbon deposited/carbon in crude oil, per ent In case when a catalyst ofthe present invention was used, formation of tar was not noticed at allduring operation. On the other hand, when alumina was used as a heatmedium, pasty tar was formed in a considerable amount.

EXAMPLE 2 parts of potassium polyaluminate (pf-A1 0 pre pared in thesame way as Example 1 and 50 parts magnesium oxide (MgO) are mixed, towhich CMC solution of 18% in concentration is incorporated in the amountof about 12%. The resulting mixture, after being kneaded, is molded intopieces having Rashig ring-like shape of 20 mm. in outer diameter, 6 mm.in inner diameter and 20 mm. in height, which are then fired at atemperature of 1500 C. The catalyst thus obtained was used in a testwherein the naphtha used in Example 1 was subjected to catalyticcracking for 1750 hours according to the cyclic system comprising 16minute cycles.

having a diameter of 20 mm. to produce a catalyst. The catalyticcracking was performed by use of the catalyst thus obtained in the sameway as Example 1. The results of this cracking were quite the same asthose shown in Example 1.

The chemical composition (percent) of this catalyst is as follows.

EXAMPLE 4 The powder of fi"-Al O (K 0-5-6Al O prepared by mixingaluminum hydroxide with potassium carbonate at the same ratio and firingthe resulting mixture at a RESULTS OF CATALYTIC CRACKING Reaction temp.,C 700 700 750 Space velocity 5 Steam-to-carbon ratio, kgJl 1 0 1. 0 1. 0

Composition ot gaseous mixture produced,

percent:

Amount of gas produced, mJ/kl. 828 701 1, 067 Calorific value, kcaL/m.12, 533 13, 218 10, 073 Etfieiency of gasification, percent. 110. 0127.8 Carbon deposited/carbon in naphtha, percent..- 0. 92 1. 10 0. 87

EXAMPLE 5 A crude oil having a specific gravity of 0.858 (/4), calorificvalue of 10870 kcal./kg. and containing 86.0% of carbon and 13.5% ofhydrogen, was catalytically cracked by using the catalyst of Example 1according to the cyclic system comprising 10 minute cycles, the resultof which are shown below.

RESULTS OF CATALYTIC CRACKING Reaction temp., C 750 800 Steam-to-carbonratio, kg./l 1. 03 800 Space velocity 0. 66 800 Composition of gaseousmixture produced, percent:

00:. 6. 47 70 0 1. 43 2. 46 CH1 24. 07 24. 27 (3-111. 1. 89 1. 4701134.- 13. 72 12. 53 0:11.. 5. 33 4. 15 (J1- o. 11 n-C4H1o..- Other 04hydrocarbons 2. 39 H 40. 56 40. 08 N 1 3. 58 2. 95 "as a; Amount of gasproduced, mfi/kl. Calorific value, kcal./m. 8473 6755 Heat produced,.THU/kl 798 832 Efliciency of gasification, percent 14. 5 89. 2

EXAMPLE 6 ,6'-Potassium-polyaluminate prepared by mixing aluminumhydroxide with potassium carbonate at the ratio of AI OO 81.45 K 8.47NiO 10.08

This catalyst composition was used in a test in which naphtha ofspecific gravity of 0.6574 (11 was subjected to steam reforming at a lowtemperature and atmospheric pressure, and the test results are shown inthe following table from which it is seen that the gas compositionalmost reached its equilibrium.

Reaction temp., C 500 550 600 Space velocity, hr 0. 5 0. 5 0. 5Steam-to-carbon ratio, H2O moi/C mol 1. 2 1. 2 1. 2 Amount of gasproduced, Nrnfi/kl" 1,469 1, 879 2, 214 Calorific value, keaL/Nm. 5,7164,174 3, 661 Efficiency of gasification, percent 111. 0 103. 0 107. 2Composition oi gaseous mixture produce percent:

002 14. 28 13. 23 10. 23 CO 3. 82 10. 84 14. 61 CH. 40. 35 23. 76 14. 54H2 40. 86 51. 83 60. 12

EXAMPLE 7 A B'-potassium polyaluminate (K O-7-22Al O prepared by mixingpotassium carbonate and aluminum hydroxide at the ratio of 1 to 3 andthen firing the resulting mixture at a temperature of 1400 C., is addedin fine powder form to a mixture of magnesium carbonate and aluminumhydroxide. The thus-obtained mixture, after mixed, is incorporated witha solution of nickel nitrate, agitated and then incorporated with sodiumcarbonate to precipitate nickel carbonate with the mixture. The slurriedmixture so obtained is thoroughly agitated and mixed, filtered and thenwashed and dried to obtain solid substances which are subsequently firedat a temperature of 400 C. to convert the nickel carbonate therein tonickel oxide. The thus-fired substances are pulverized, blended withalumina cement and molded into pellets which are then heated at atemperature of 250 C. in steam to produce the desired catalystcomposition in the pellet form. The chemical composition (percent) ofthe catalyst composition so produced is compared with that of theconventional commercially available catalyst composition (percent), asshown below.

Ignition less 810: FezOa A110; 080 MgO N10 K20 Catalyst composition ofthis invention 8. 05 0. 09 0. 04 63. 99 7. 99 3. 17 11. 66 5. 01Conventional commercially available catalyst composition 11. 74 12.77 1. 14 33. 97 9. 94 7. 03 16. 66 6. 85

3 to 1 and firing the resulting mixture at a temperature of 1400 C. isfinely powdered and molded into pieces having Raschig ring-like shape of17 mm. in outer diameter,

In the following table, there are shown comparative data obtained at theinitial stage of the operation in which these catalyst compositions wereused in the con- 5 mm. in inner diameter and 17 mm. in height which aretinuous steam reforming of naphtha, whose boiling point range is from 40C. to 170 C., specific gravity is d =0.71, at a pressure of 20 atm. for24 hours.

Commercially available Catalyst of this catalyst inventionReactiontemp..C 700 750 800 700 750 800 Space velocity (vol./vol./hr.)1.0 750 800 700 750 800 Steam-to-carbon ratio (11:0

mol/C mol) 338 750 800 700 750 800 Amount of gases produced,

Nm. l 2,985 3,311 3,585 3,186 3,380 3,720 Efiiciency of gasification,

kcal. cal 122 123 128 123 125 129 Amount of carbon deposited,

percent 1.2 1.1 0.1 0.4 0.3 Tr. Composition of gaseous mixture produced(vol. percent 2 This catalyst composition of this invention, which wascharged into a tubular reactor of 4 inches in inner diameter and 19 feetin length, could be used as such for 4500 hours without lowering itscatalytic activity. The used catalyst composition withdrawn from thetubular reactor has the following chemical composition which shows thatit extremely slightly decrease in amount of potassium oxide as comparedwith the conventional ones. In the conventional catalyst, pulverizationof catalyst in the lower portion of catalyst zone due to deposition ofcarbon was noticed in a considerable amount. This phenomenon, however,was not noticed at all in the catalyst of the present invention.

amount of the potassium, and then washing away soluble potassium of freeform the fired mixture) is added in fine powder form to a kaolinite clayat the ratio of 1:1. The thus obtained mixture is incorporated with asolution of nickel nitrate and then mixed with each other. The resultingmixture is incorporated with sodium carbonate thereby precipitatingnickel carbonate within the mixture. The slurried or pasty mixture soobtained is mixed thoroughly under agitation, thereafter filtered andthen washed with water to produce solid substances which aresubsequently dried and fired at a temperature of 400 C. to convert thenickel carbonate to nickel oxide. These fired substances are pulverizedand formed into pellets having the following chemical composition(percent).

shown in Example 7 when subjected to the same test as Example 7.

EXAMPLE 10 The catalyst of potassium polyaluminate (,B-Al O used inExample 1 is dipped into a solution of cobalt ni- Ignition loss S10:FezPa A1203 C80 Mgo N10 K20 Catalyst composition of this invention 0. 00. 04 69. 75 s. 69 3.46 12.70 5. 26 Conventional commercially availablecatalyst composition T1- 15. 01 1. 34 40. 12 11. 70 9. 85 19. 44 3. 04

EXAMPLE 8 the following chemical composition (percent).

Ignition loss Trace SiO 0.10 F6203 A1 0 87.25 CaO 0.01 MgO Trace NiO5.40 Na i) 7.21

The catalyst composition showed approximately the same high activity ina laboratory-scale test as that obtained in Example 7, and on the otherhand it allowed carbon to deposit thereon in a small amount when put toa prolonged use (about 1000-hour use) in a pilot plantscale test. As itscharacteristic, however, it could easily be regenerated without damagingit because it was strong in structure and the carbon deposited thereoncould readily be blown off by use of an inert gas such as N gas or thelike.

EXAMPLE 9 fi"-Potassium polyaluminate (this being prepared by mixingaluminium hydroxide and potassium carbonate at the ratio of 1:1, firingthe resulting mixture at a temperature of 1300 C. to diffuse aconsiderable part of the trate, incorporated with 1% and 0.5% of C00 andthen heated at a temperature of 600 C. to remove nitric gas.

The catalyst thus obtained was used in the catalytic cracking of thenaphtha of Example 1, the results of which are as follows.

Catalyst B-AlzO; incorpofl'-Al20a incorporated with 1.0% rated with 0.5%of C00 0! C00 Reaction temp. C 750 800 750 gtea r i-tta oargooii ratio,k1 1.01 800 750 5% pa ve 001 y 1.08 Composition of gaseous mixture 800750 800 produced, percent:

002 8. 35 20 7. 49 7. 70 14. 73 60 5. 90 15. 70 10. 11 6. 93 16. 75 11.40 1. 11 0. l. 1. 51 H 5. 38 3. 70 18. 81 10. 74 Call 4. 30 0. 65 6.12 1. 03 Other 04 hydrocarbons 1.00 5. 20 132 55. 30 60. 25 37. 51. 80

'1 02 Amount of gas produced mi /k 1, 480 2, 185 830 1, 630 Calorificvalue, ken/m 34s a, 92s 9, s25 5, Heat produced. J HU/kl 790 857 810 842Eflicieucy oi gasification,

percent 100. 2 114. 2 110. 0 113. 5

EXAMPLE 11 The catalyst of potassium polyaluminate (fi'-Al O used inExample 1 is dipped into a solution of chrome nitrate, incorporated with1.0% of Cr O and then heated at a temperature of 600 C. to remove nitricgas. The catalyst thus obtained was used in catalytic cracking of thenaphtha of Example 1, the results of which. are shown below.

Reaction temp., C 750 800 Steem-to-carbon ratio, kg./l..; 1, 01 800Space velocity. 1. 08 800 Composition of gaseous mixture produced,percent:

C01 9. 25 6. 58 C O 9. 36 20. 50 C' 11. 76 7. 53 Ca'FIr 2. l2 1. 06 CAL11. 64 4. 04 CaHg 5110.. 3. 39 0. 44 Other C. hydrocarbons 3. 30 0. 5149. 20 59. 30 No On Amount of gas produced, mfi/kl 1, 435 2, 370Calorlfic value, kcaL/m. 6, 250 3, 750 Heat produced, JH U/kl 897 889Efiiclency ot' gasiflcatlon, percent. 116 161 What we claim is:

1. In a process for catalytic cracking of hydrocarbons, the improvementwhich comprises employing as a catalyst a composition comprising (a) atleast 2% by weight, calculated as an alkali metal oxide, of at least onealkali polyaluminate selected from the group consisting of fi'-aluminaand 6"- alumina, and

(b) a different refractory catalyst carrier material.

2. In a process for steam reforming of hydrocarbons, the improvementwhich comprises employing as a catalytic composition a mixtureconsisting essentially of (a) at least 2% by weight, calculated as analkali metal oxide, of at least one alkali polyaluminate selected fromthe group consisting of p-alumina and p"- alumina, and

(b) a different refractory catalyst carrier material.

3. In a process for steam reforming of hydrocarbons, the improvementcomprising employing as a catalyst a composition comprising:

(a) at least 0.5% by weight, calculated as an oxide, of

at least one member selected from the group consisting of chrome oxideand an oxide of a metal of Group VIII of the Periodic Table, and

(b) at least 1% by weight, calculated as an alkali metal oxide, of atleast one alkali polyaluminate selected from the group consisting ofp'-alumina and p"- alumina.

4. In a catalytic process for cracking or steam reforming ofhydrocarbons, the improvement which comprises:

using a substantially neutral catalyst consisting essentially of (a) atleast about 1% of at least one alkali metal polyaluminate (based onweight of alkalimetal oxide) selected from the group consisting of ,fial umina and ,6"-alumina with at least 0.5% by weight of chrome oxide orGroup VIII metal oxide, and

(b) refractory catalyst carrier difierent from (a).

5. The process of claim 4 wherein material (a) is present in an amountsufficient to inhibit carbon deposition.

6. The process of claim 4 wherein the catalyst carrier comprises CI2O3,CaO, MgO, SiO- TiO ZrO A1 0 01' 3Al O -2SiO 7. The process of claim 4wherein the alkali metal polyaluminate consists essentially of R O-7-8A1O wherein R is Na or K.

8. The process of claim 4 wherein the alkali metal polyaluminateconsists essentially of R O-5-6A1 O wherein R is Na or K.

9. The process of claim 4 wherein the catalyst comprises at least 5% byweight of K 0.

10. The process of claim 4 wherein the catalyst comprises at least 5% byweight of Na O.

11. The process of claim 4 wherein said alkali polyaluminate is sinteredand is impregnated with the 0.5% by weight chrome oxide or Group VIIImetal oxide.

12. The process of claim 11 wherein the catalyst is formed as a fired,shaped article.

References Cited UNITED STATES PATENTS 2,454,227 11/1948 Smith et al252-434 OTHER REFERENCES On the Structure of Alkali Polyaluminates,Yamaguchi et al., Bulletin of Chem. Soc. of Japan (January 1968).

S. LEON BASHORE, Primary Examiner R. PACE, Assistant Examiner U.S. Cl.X.R. 48197 B 23x2?" mm 8m PATENT OFHCE CERTIFICATE OF CORRECTION PatentNo. 3, 3-17, 26 D ted Jude 1974- Inventor(s) IGOI'O Yamaguchi, et 81.

It is certified that error appears in the above-identified patent andthat said. Letters Patent are hereby corz ected as shown below:

Claimll, lines 2-3, cancel 0. 5% b weight" Signed and sealed this 24thday of December 1974.

(SEAL) ACCESt:

McCOY M. GIBSGN JR. 0. MARSHALL DANNY Attesting Officer Commissioner ofPatents UNITED STATES PATEN? OFFICE:

' CERTIFICATE OF CORRECTION Patent No. Dated June 18,

Inventor(s) lGoro Yamaguchi t a1 It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column line 8, change Rules" to ---results.

" ime 22, change 1260" to --12s5--.

line 23, cha ge "7313" to --7319--. l i ne 24, chenge "12 4. 9H0 --124.0-'-'.

line 71, change "o. 05 to --s. 05--. Column 9 line 15, change ''15. 55"to ----14. 55-. Y

Signed and sealed this 5th day of November 1974.

(SEAL) Attest:

MCCOY 1 4. GIBSON JR. 7 c. MARSHALL DANN Attestlng Officer Commissionerof Patents

